I don't get all the hate I thought the whole series was a bit slow, and that's not a bad thing. Slow in the sense it was focused on acting, on dialogue, on political and cultural intrigue. I stopped watching in the middle of Season 3 because I started other series that are more to my taste.
But I came back to finish because I love history, period pieces and I'm really curious about this idea of "what if the Nazis won?". Also, the quality is au rendez-vous.
Now, the funny thing is that I only realized there was sci-fi in this during season 3. I had to come on IMDb to make sure. Then I learned it was based on short book by Phillip C. Dick. Had no idea.
Contrary to most reviews here, I got more interested in the last two seasons. I didn't mind the end at all. I wasn't expecting something predictable and it wasn't. I don't mind cryptic or opened ended story.
John Smith has been given this name to say that anyone could become him (most common first and last name). Him and his family are my favorite intrigues. I didn't relate much to some of the other main characters like Juliana. That's one of the reason I'm no giving more than 7/10. It didn't blow me away but I'll remember a great deal of it and will talk about it to whoever will listen.